The present invention relates to improvements in on-line liquid samplers and, more particularly, devices and arrangements of this kind for periodically withdrawing small samples of a liquid flowing through a pipe. A device of the kind mentioned has been disclosed in our U.S. Pat. No. 4,009,617 issued Mar. 1, 1977. The description and drawings of this older patent should be incorporated herein for purposes of disclosure.
In our earlier patent there is shown and described an instrument which is designed to collect composite samples of liquids as they are pumped through pipelines. The system uses two valves to regulate the flow of product that is sampled. The flow past the first valve which may be referred to as a check valve, lets the sample product flow into a measuring chamber which contains a flat elastomer diaphragm. When air pressure is applied to the back of this diaphragm, it directs the sample into a collection container by moving the check valve so that it closes the sampler opening to the pipeline and pops open a spring loaded self-restoring valve to allow the sample to exit from a discharge port into the collection container.
Since the two valves alternate in opening and closing, this sample design offers a high degree of sanitary protection for the pipeline being sampled. This alternating action keeps the pipeline from ever being open to the atmosphere in the plant and prevents sampled product from reentering the pipeline once it has been removed.
There are situations, however, such as when it is desired to composite-sample pipelines containing sterilized products where this design is still not sanitary enough. This is because of the problems associated with trying to mount a sampler that has been sterilized, say through autoclaving, on the pipeline without compromising the sterility of the sampler and the pipeline.